US forces intensified their offensive against suspected guerilla targets, killing seven people preparing to fire rockets at an American base near Tikrit and pounding positions near the Syrian border and in Baghdad with air assaults, military officials said.

President Bush vowed to keep US troops in Iraq "until the job is done" as the top US administrator Paul Bremer prepared to meet the Interim Governing Council on ways to speed the transfer of power to Iraqis.

Mr Bush said US forces would not leave Iraq or Afghanistan as long as Saddam Hussein and Osama bin Laden remained at large.

"We will find them. OK? Yes, we're not pulling out until the job is done," he told British journalists ahead of his visit to London next week to meet British Prime Minister Tony Blair.

Asked if that included finding Saddam and bin Laden, he replied, "Yes, that's part of it."

Even as the aggressive US counter-punch, dubbed "Operation Iron Hammer," continued, small roadside bombs planted by guerillas killed three US soldiers.

Two soldiers from the 4th Infantry Division were killed late on Thursday and three others were injured north of Baghdad near the city of Samara, officials said.

In the central Baghdad district of Khadra on Friday morning, a roadside bomb killed one US soldier and two others were wounded.

"We heard an explosion and woke up. When we went outside we saw two injured soldiers," Jawwad al-Hafaji, an Iraqi who lives in the Khadra neighbourhood, said. "I think one of them was dead because he was covered in a sheet."

One US contractor was killed near the city of Balad when gunmen attacked a convoy on Thursday, the military said.

More than 160 American soldiers have been killed since President Bush's May 1 declaration of an end to major combat operations - 42 of them died this month.

So far more than 400 soldiers have died in combat, from accidents and other causes since the US-led invasion in March.

After a string of deadly bombings and rocket attacks, the Pentagon last week announced plans to seek and destroy insurgent operations.

In Saddam's hometown of Tikrit, north of Baghdad, seven Iraqis suspected of intending to launch rocket attacks on coalition forces were killed when an Apache helicopter fired at them several kilometres from a US Army base, officials said.

Near the Syrian border, US F-16 fighters dropped two satellite-guided bombs on a building believed to be used by guerillas as a staging base for attacks and ammunition store.

Separately, the Pentagon's senior policy aide said US forces "may not find" significant stores of the Iraqi weapons upon which the Administration based its case for war.

The official, Undersecretary of Defence Douglas Feith, said Saddam "posed a serious threat" with or without the stockpiles, because he had the means to produce weapons of mass destruction quickly and get them into the hands of potential terrorists.

"We haven't yet found, and may not find, stockpiles of chemical or biological weapons," Mr Feith told the Council on Foreign Relations.

Saddam used and maintained such weapons more than a decade ago and never verified their destruction to the satisfaction of United Nations inspection teams, despite a 1991 pledge to do so.

Former UN weapons inspector David Kay is leading a team of more than 1200 US troops and inspectors scouring Iraq for such weapons.

Mr Kay has announced that he possesses documented evidence of a sophisticated and secret network of programs to make chemical and biological weapons, but has not discovered significant caches of the weapons themselves.